It has been a while since I had my OD apart, but I think the OD drive is held
in place with a cross bolt. Remove the bolt and the drive spindle is able to
be removed without much trouble. It can almost certainly be done from the OD
access hole in the transmission hump on the passenger side.
Almost certainly the drive gear has the wrong number of teeth. I forget how
many teeth it is supposed to have, but someone here probably knows. 15 I think
for the A-types.
You do not say if you are reading high or low. If it is reading high, the
drive gear has too few teeth (probably by 1 or at most 2). It the speedo reads
low, then it has too many teeth.
An adapter gearbox in the speedo cable is a reasonable alternative. They can
get the calibration VERY accurate with them. I am told that there are 4 gears
which are interchangeable to give almost any ratio imaginable. APT speedo can
do it. http://www.gaugeguys.com/ratioadapt.htm
-Tony
Hi Anthony, My speedo says 1000, but Ive seen them(late model) that say 1120.
I understand the change came at CF35000. Im not sure if this overdrive even
came out of a TR6, but it works flawlessly, so Im not too unhappy. I made some
calls today to speedo shops, and they can put a ratio converter in my
speedometer cable, which seems like the easiest way to go. My speedo is
reading about 15% high, but I need to do some measured mile testing to get a
fairly exact number before I go for the converter. Changing the speedo
driving gear looks like a pretty involved job(like a professional) so thats
last resort. Thanks for the reply, John
Anthony Rhodes wrote:
John, do you know what year the OD is from?
For some reason I thought that all the TR6 speedos had the same calibration:
1000.
What is the calibration printed on your speedo?
Probably you could get the correct speedo drive (at the OD) for your speedo and
correct it. Otherwise get the correct speedo....
-Tony
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